Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello, good day and thanks for your question. I understand that you are looking into extending your Microsoft 365 subscription.
Kindly take note that, if the current Office or Microsoft 365 product was provided by the PC manufacturer or the seller as a prepaid subscription with a certain validity period, you may not be able to extend it with your existing subscription.
However, you can still check and reach out to the support team at https://support.microsoft.com/en-us/contactus/ and then click on Microsoft 365 and then click Get Home Support and then type in Billing question and click the blue button that says Sign in to contact Support and login and proceed from there.